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Topic: Banjo Build (Read 80582 times)

So a while back I had the silly idea of trying to build banjos to sell. And for a good while I was building stupid tools to do jobs the hard way.

Before I built that drum sander I decided to just start actually building a banjo to see how it goes. Then I got distracted again by a friend asking me for help in building skateboards and built that drum sander. I finished the sander but the skateboard thing fell through so I'm getting back to continuing that banjo.

That's my life story out the way. So I started by making some wooden hexagons. The main wood i'm using is meranti, a sort of cheap knock-off mahogany.

Despite being careful, I didn't get the angles right. I really have no idea how people manage to do those fancy segmented turnings. I guess they must cut the last segment to fit.

They were glued in two halves and then the joining faces were sanded flat.

Anyways after being left in the house for two months the meranti hexagons held up fine, but the top one made from goncalo alves shrunk enough to make a huge gap, the individual segments also twisted a huge amount. It's not a very stable wood, evidently.

The idea is that fancy banjos use a metal tone ring that sits between the skin head and the pot, and that gives it a brighter tone. So instead of that I'm going to use a hard wood as the top layer in the pot. That said, i'm not a big believer in tone. I guess there are differences, but which one is better is highly subjective. But it's still something I wanted to try.

The meranti hexagons didn't warp at all, but weren't perfectly flat to begin with. So I sanded them true on the drum sander.

These were then glued into a stack, on a board of plywood. It was awkward with the thing sliding about on the glue. If or when I do this next, i'll probably drive some pins into the wood to prevent that. A layer of paper should hopefully make it possible to separate the pot from the plywood once it's round.

There was still that top layer to sort though. The goncalo alves was too warped to try forcing flat, so I went through my basket of hardwood to try find something else. I first tried using a piece of chechen, and after cutting it up I realised I didn't have enough wood. I'd checked to see how stable chechen was online before cutting it up, and it seemed to rate fairly well. But I was fed up at this point and decided to just cut some apple wood and see how that goes.

That was then glued up.

Tomorrow I'm planning to build a rubbish wood lathe to turn the inside of the banjo. The outside will probably be sanded on the spindle sander. I'd actually built that sander with the intention of using it to sand banjo pots round internally, but i've since deiced that it wasn't the best of ideas. I guess i've warmed up to the idea of awkward dangerous looking wood lathes after building the drum sander.

I measured up some various scraps in the garage and here's what i'm going with so far. I'll probably add a bit more bracing to the headstock side of things, but there's no point in drawing that up I suppose.

Simon, have you considered splining those end grain joints? Make a jig for your tablesaw and run the pieces through, then rip up some spline stock and glue it in. You can do that to individual pieces before assembling, or do it at the joints to the ring you.ve already made. It will be easier and much better than doweling for this kind of joint -- gluing surface area where it should be, and grain running across the joint. And you don't need to buy (or make) dowels. If you really want to lock it, spline, and then dowel from the face through the spline, ie wooden fasteners.

Simon, have you considered splining those end grain joints? Make a jig for your tablesaw and run the pieces through, then rip up some spline stock and glue it in. You can do that to individual pieces before assembling, or do it at the joints to the ring you.ve already made. It will be easier and much better than doweling for this kind of joint -- gluing surface area where it should be, and grain running across the joint. And you don't need to buy (or make) dowels. If you really want to lock it, spline, and then dowel from the face through the spline, ie wooden fasteners.

Oh by pin I meant like veneer pins, tiny nails. Just tapping them in a bit and cutting most of the rest off, so that it doesn't want to slide as much when clamping up each layer. I'm a little worried that I might not have gotten each layer lined up properly and won't be able to turn it 11 inches. But if that happens I guess i'll just turn one of the layers a bit narrower than the top, and try pretend it's something decorative.

I'm not expecting the end grain joints to hold that strongly, most of the strength will come from the edge grain joints with each layer.

I have been making 5-string banjos for 51 years now. One of the things that makes the job a lot easier is to cut your "shell wood" into thin (call it 2-2.5 mm thick) strips and laminate them inside of a (hollow) circular jig. Here in the U.S. nearly all banjo heads are 11 inches in diameter -- making 10.950/10.900 inches the correct OD for the shell. The circular clamping jig I use has the OD set to 15 inches -- which means that I can use it in my table saw to "trim off" the (inevitable) "mismatch" at the top and bottom edges. I "wax" the ID of the jig to keep glue from sticking to it.

My "ID Clamp" is an inner tube from a hand truck (5 inch hub, as I recall) that fits on an inner (about 7.5 inches OD) piece with an extension that allows me to inflate it to clamp each "layer" as I laminate the shell. I find that (about) 30 psi works really well.

I normally make my shells 3.5 inches tall, so I start off with a piece of wood that is 3.75 inches wide and 34.75 inches long. I "dress" the face of the stock on my joiner and slice off a piece on my bandsaw, take it back to the joiner, and repeat until I have all my strips. I then use my thickness sander to finish each "layer" to thickness (.090 inches for my approach). I cut them to length, steam them, and insert them into my jig and force them to round using the "ID Clamp." The "outer joint" of the shell gets located under the heel of the neck, so the slight "mismatch" is (virtually) never seen.

I make my frailing banjos with a (roughly) 10 mm thick shell. Bluegrass banjos get a (roughly) 20 mm thick shell. After the slightly over-tall shell is complete, I return it to the "circular jig" and use that to trim it to length. I then glue "strips" to the bottom of the shell and trim them flush using a trim-router. I can then, if so desired, route a "perfling rabit" for final clean-up trim.

I have been making 5-string banjos for 51 years now. One of the things that makes the job a lot easier is to cut your "shell wood" into thin (call it 2-2.5 mm thick) strips and laminate them inside of a (hollow) circular jig. Here in the U.S. nearly all banjo heads are 11 inches in diameter -- making 10.950/10.900 inches the correct OD for the shell. The circular clamping jig I use has the OD set to 15 inches -- which means that I can use it in my table saw to "trim off" the (inevitable) "mismatch" at the top and bottom edges. I "wax" the ID of the jig to keep glue from sticking to it.

My "ID Clamp" is an inner tube from a hand truck (5 inch hub, as I recall) that fits on an inner (about 7.5 inches OD) piece with an extension that allows me to inflate it to clamp each "layer" as I laminate the shell. I find that (about) 30 psi works really well.

I normally make my shells 3.5 inches tall, so I start off with a piece of wood that is 3.75 inches wide and 34.75 inches long. I "dress" the face of the stock on my joiner and slice off a piece on my bandsaw, take it back to the joiner, and repeat until I have all my strips. I then use my thickness sander to finish each "layer" to thickness (.090 inches for my approach). I cut them to length, steam them, and insert them into my jig and force them to round using the "ID Clamp." The "outer joint" of the shell gets located under the heel of the neck, so the slight "mismatch" is (virtually) never seen.

I make my frailing banjos with a (roughly) 10 mm thick shell. Bluegrass banjos get a (roughly) 20 mm thick shell. After the slightly over-tall shell is complete, I return it to the "circular jig" and use that to trim it to length. I then glue "strips" to the bottom of the shell and trim them flush using a trim-router. I can then, if so desired, route a "perfling rabit" for final clean-up trim.

That's some good information. Thanks!

The reason i'm going with the segmented construction is because I was hoping to be able to make some fancy segmented bowl style patterns from the wood. Although i'm just trying to get anything working right now.

My current banjo is cobbled together from a banjo neck, some hardware, and a wooden box that had paints. Kinda like a cigar box banjo but not at all solidly constructed. The whole thing can flex too easily and it goes in and out of tune. I'm long overdue a replacement.

I've all but finished that rubbish lathe. Apologies for the busy photos, it's hard to see whats what.

Turned the faceplate round without any issues so i'm fairly convinced it should work.

Also I'm pretty pleased with that router base. It's just screwed into the side of the headstock to hold the drill in place. It's a pretty cheap and flimsy thing, but i've been finding all kinds of uses for it since it grips regular drills. The router/ laminate trimmer itself also works as (and is pretty much built exactly the same as) a die grinder. I found it in a second hand shop.

Didn't get anything done yesterday since I needed some 9mm plywood. I usually buy it from a builders merchants in full sized boards, quartered so I can get them home, but without a car it's a weekend thing. Had a while to wait for the bus up in Consett today so I decided to head to the hardware store and see if maybe they sold some. And sure enough, they did. For a fair price too. £6 for a quarter board.

The hardware store is called Gralands and it's well worth checking out if you're in the area. It's amazing what they fit into a small place. I keep thinking I might take some photos of the place but it's a bit of a dorky thing to do, but afaik hardware stores like that (the sort that sell screws by weight) are a rare thing.

Anyways it's now pissing it down with rain so I've got everything up on the benches in case the garage floods, so there's not alot to do till it stops.

Here's what happens when I try be clever. Instead of just clamping a bit of plywood to the table I thought i'd put some threaded inserts into the table to bolt a fancy thing to. I put the first threaded inserts in the wrong place, down at the bottom of those slots, and then realised that the banjo pot would cover them so I couldn't use that to screw it down, so I put a couple further up. Which I put too high so I had to sand the middle part longer.

I also made a mess of trying to make the thing. You can see all the lines where I kept bungling it up, and the slots are terribly long (and cut roughly with a jigsaw) since I kept putting them in the wrong place too.

I also bungled up transferring the banjo pot from the 18mm ply to the 9mm ply, by forgetting to first draw a circle on it so I could find the center again. So I'm probably going to print out a circle and try find a place to fit it, then use that to find the center. At least the paper thing worked and it was possible to remove it from the plywood, although now i'm worried it wont be able to survive the force of being turned on that lathe.

Spent the last couple days doing other things for the most part. I'm having trouble again with the sanding sleeves on the spindle sander. I'm mostly going through each half-assed idea I can think of to avoid doing the best solution and copying commercial sanders (that use a rubber block that gets compressed down with a nut, to expand out and grip the sleeve).

Another vaguely interesting thing i've been doing is editing a clip show for some sort of conference (I don't know what to expect but I was asked to do it). Condensing 4 projects into a 5 minute video turned out to be a difficult task. I really expected it to be a quick job but since I can't use the rendered files (they've got baked-in commentary) i've had to sort through all the source clips. So it was almost equivalent to editing 4 videos back to back. I didn't have to record commentary at least.

More fussing with the spindle sander with no luck. I think what I might try doing is cross drilling the spindle and putting a pin in, then making a plywood sleeve of sorts that I'll just glue the sandpaper to directly with a slot to index with the pin. Might make a few sleeves while i'm at it.

I've also got a slight alignment issue that I noticed pretty much after I built the thing, but I didn't give it a whole lot of thought till now. The motor isn't mounted parallel to the rails that it slides on, and fixing that will probably require an almost full disassembly. It causes the spindle to move forwards a bit as it raises up. While I can get around it affecting the work by just switching off the oscillating for a final pass, I doubt it's doing the sandpaper any favours to be heavily pushed into the work each time the spindle moves upwards.

I should've fixed this a long time ago but I tend to leave stuff like this until it's absolutely necessary.

Yet more fussing. Alot of time is spent waiting for glue to dry. I've been trying to bore a 20mm hole into the plywood spindle with no luck. Trying to make crappy reamers out of bits of barstock. That works for shallow holes but it's killing the drill and just causing alot of friction trying to do it with something so deep.

I did think for a bit about making some sort of boring tool using a bit of square high speed steel but at this point I should really just go out and buy a damn 20mm drill. So i'm going to do that tomorrow.

It's always these little jobs that seem to take the longest.

(and in all honesty, I could probably just turn the outside of the thing on the rubbish lathe i'd made too, but i'm dead set on doing it this way. Maybe just to prove the sander wasn't a waste of time).

Got a drill bit. An auger, actually. I'm still not sure what advantages augers have over anything else (maybe if you insist on using an old bit and brace), but they were alot cheaper and longer than the blacksmith drills. I'll probably regret being so tight when I need a 20mm hole in metal.

But anyways, it made a nice hole just the right size. But now i've got yet another problem with the spindle no longer being in axis with the motor's spindle. My best guess is that a bit of sawdust is trapped somewhere in between but it's a bit awkward to get at to see clearly or clean it. So I've got no choice but to disassemble it. Could also just be a problem with the spindle not being balanced, and if that's the case then there's probably no hope of fixing the problem. Garage is a total mess though and needs a good tidying up so I have my workbenches back. Had another thunder storm so I piled everything off the floor that I didn't want to get potentially wet on the benchtops.

This project is going at a glacial pace. Hopefully I've got everything i'll need for now though and can get back to it. But spending the weekend fussing with the sander has killed alot of my enthusiasm.

I've been holding off posting pictures since I thought this whole spindle sander tune-up would be a quick and boring job.

Got the spindle trued up. Not sure how it ended up shifting out of alignment. Maybe the metal settled or something when I drilled that hole through the middle. It was trued up the same way as when I built it, with scraping the mating face. Ended up reducing the runout to damn near zero.

Hot off of that I thought i'd tackle the spindle not being parallel to the rails and... well I've got no easy way to adjust it, so after alot of thinking about which way things needed to move I shaved a bit of wood off the inside of the lower motor mounts (the ones held on by a jubilee clip) and tried shimming them. Didn't expect to get this perfect but I figured I could improve the situation a bit.

And I think when I put the holes in to begin with I must've just gotten lucky with the placement because I could not get the thing back together at all without it jamming up once the jubilee clip was tightened. Spent more than an hour trying to brute force it with various paper shims. Another interesting thing was inspecting the wear inside the thing. The pin that the crank arm connects to to lift the motor up and down has become fairly loose and it'll probably eventually split the plywood. A few posts ago I was patting myself on the back for a good design but I think this is a weak part and could probably do with some fixing up too. A couple of screws might just do the job in holding the plywood together against splitting.

Anyways I'm probably going to have to think up a solution for the lower mounts that makes them more easily adjustable. The alternative could be to make the parts again, and use the spiked ends of the bars once more to locate the hole centers. Perhaps that way is more accurate than I give it credit for.

Here's what i've come up with. Flat wooden block that another screws into. There's 4 screws so a jubilee clip can fit between them. I forgot to model the slot required. But it should give fairly easy adjustment in alot of directions (screw holes will be enlarged and washers used to give it some play). Shims can also be used for the other directions, and being square it should be easier to guess where to put them and how much to use. It should also be possible to adjust the thing without disassembling it.

I was wondering why I didn't do something like this the first time around, but then I remembered I didn't have a tablesaw back then and this would've been difficult to do well on the bandsaw.

Simon, you're doing the right thing, making things easier on yourself for the future. You'll save this time and a lot more down the road, make better parts and reduce mistakes and frustration. Good investment!

Simon, you're doing the right thing, making things easier on yourself for the future. You'll save this time and a lot more down the road, make better parts and reduce mistakes and frustration. Good investment!

Yeah hopefully it works out. I try to make things as adjustable as possible now since expecting things to just work out never.. works out. One really stupid thing I did when building the sander was gluing the trunnions onto the table, and then epoxying threaded rod into the sides of the thing. So it's impossible to take the table fully off unless I want to break the glue joints. If I was doing it again i'd use knobs and threaded inserts. I suppose I could still do that but i'd rather not give myself more work.

Right now i'm waiting for glue to dry. I spend my life waiting for glue to dry. It's the real downside of working with wood (aside from the dust). Wish I had the forethought to do that last night. I've sharpened the bandsaw blade in the meantime and, even though I mangled alot of the teeth, it cut's like new.

Depending on the job size and strength needed, I tend to use 5 minute epoxy for small jobs for just that reason. Big jobs, it's way too expensive. Same for highly absorptive jobs. Also it's not as strong as slower epoxies, and not entirely waterproof. But it is very useful in a lot of situations.

If the type of glue connection can use it, I also sometimes use contact adhesives, to speed up the work. Laminating sections of casting patterns is an example. Again, not tremendously strong unless the glueline surface area is high and stresses are low/area but certainly adequate for certain situations, and very fast.

I tend to back up weaker gluelines with fasteners -- they are fast and prevent shifting and splitting, and it doesn't take many to do that. It oftan also means the part can be used imediately in building up a structure, since the fastener is a clamp. Dowels can work as fasteners in that way, too, for an all glued structure. Treenails are the ultimate, that way.

More problems. I've ran out of 2 inch screws and need to buy some more, plus the forstner bit I used to originally drill holes at 19mm/ 3/4" is the one I'd turned down to 18mm when making that bike. So I either need to get a new forstner bit or make some new bushings at a wider outer diameter. Either way i'll have to buy something before I can continue.

Might as well continue with the theme of moaning about everything. Must've pulled my back somehow yesterday and had an awful nights sleep with it. Took some codeine and got back into the garage for a bit. I'd forgotten to record cutting the blocks so I'll probably make another one and record that after I get the sander back where it belongs since it's currently on top of the tablesaw.

Got these bits on and close enough to parallel. Unfortunately it turns out today is Good Friday so no shops will be open to get some screws.

I'm thinking that while i'm at all this I might try make a new rail and spindle (or part of one) without using the lathe, to make a dedicated spindle sander update video. I know the rails could be made without a lathe since they don't need to be that accurate and can be scraped and filed square, but the spindle might be trickier. Tilting the drill press table to be parallel to the drill's spindle and fixing the steel bar on square might get it accurate enough to work.

I find update videos a little cheesy so I might put something else in too. Considering doing a segment on how I feel about 'taking care of tools'. Stuff like crashing a lathe or dropping a chuck onto the ways is worth avoiding, but you get people out there who fuss about things like using chisels to open paint tins, or a drill as an improvised mallet while it's already in your hand. It's not that interesting a video topic though.

Ground down a (supposedly) 20mm spade bit to cut a tight hole for the bushing.

Over-did it a little and it took alot of pressure to press the things in.

Didn't check the drill press table before drilling the hole and it was a fair ways off of square, so it was alot of shimming to get this thing to slide. It's still fairly tight and could probably do with a bit more work. But if I remember right, it was never really that smooth a slide to begin with. It'll probably wear itself in eventually.

Pressing the second one in using a very long cheating bar ended up shearing the vise's screw off towards the end. Just means the vise has a smaller travel now, but I'm almost glad this happened. I never expected this vise to last very long, being a cheap one at reduced price from LIDLs. But 3 years of very heavy abuse (whacking it with a hammer n all) it's held up pretty well.

It'll give a lead-in if I do make that video segment about taking care of tools. If it was some swish expensive record vise i'd be compelled to take care of it, and probably not get as much use from it.

Anyways I drilled the second hole a ways out so it's going to require some fairly heavy shimming. I'm taking a break for now though.

I think all of this is proving that I was just very lucky the first time I built this.

Little cousins came over and hung out in the workshop and helped out while I reenforced the wood around that pin that was coming loose and then reassembled the thing. That again was a hassle. The connection between the yoke and the windscreen wiper motor was slipping so I tried shimming it up to tighten the joint. Worked for a bit then came undone (which won't be too big a hassle to fix). But just before it came undone I noticed that the spindle was tilting back and forth as the motor went up and down; a problem that wasn't happening before.

It seems very sturdy trying to shift it about by hand but maybe the torque of the motor was enough to slide the new lower motor mounts back and forth. If that's the case then i'll probably put some plywood blocks on the front and backs of them to reenforce them in their position. Although at that point the design won't be so elegant and will look a mess. The other option might be to make some largeish washers to go under the heads of the screw that hold it on, so I can really tighten them down to try get it to grip. But that'll then probably compress the shims more and require more fiddling and adjusting.

It's a shame because I really thought I had it. I guess the good news is that the spindle is running very true and doesn't seem to be precessing or vibrating at all. I was worried adding that pin across it would throw the balance out.

Used some thicker and longer screws on the motor mounts and fussed with shims to get them really cranked down, since the smaller ones were stripping the wood. It slides alot smoother now than before too.

https://www.youtube.com/watch?v=SWw5GqIPqEI#t=8m24s In this bit of the video you can see the windscreen wiper motor moving back and forth. I never got around to fixing that since it didn't seem to be causing any trouble but i'd noticed that the bushings in the crank arm are surprisingly worn and this probably didn't help.

Welded a brace on. 2mm steel with 3.2mm rods with a cheap buzz box. Unfortunately someone borrowed my better welding mask, took it to work, then got laid off so i'm using the rubbish hand visor that came with the welder.

I'm doing it outside since there's still piles of sawdust about to catch fire.

Not the prettiest welds but they're plenty strong enough.

To try get the motor to grip the yoke better I turned a thing. One part of making stuff that I find funny is trying to come up with names for all the parts. Got no idea what i'd call this though. An insert? A flange?

Whatever it's called, I cant mount it in yet since I've ran out of epoxy on a bank holiday Monday. So i've reached a dead end for today.

Continuing with the topic of abusing tools, I turned down this bedford socket so it could reach inside the part i'd made.

I'm doing it outside since there's still piles of sawdust about to catch fire

where's your sense of adventure??

looks like your making progress, im sure you'll get there in the end

The adventure in this case would be going down into the garage every half our to make sure no sparks snuck into a pile and left it smouldering for a while before it fully caught light. I have managed to set oily rags on fire before while welding though!

Thanks for the encouragement. I'm really wishing I just left the thing misaligned though so I could move on with the project. Turning the pot round was supposed to be the easy part!